The assumption that the US has the technological know-how to cripple a competing nation has always been just that: as assumption. In a recent sit-down interview, however, a former spy chief confirmed that America has already waged cyber attacks.

Mike McConnell, the former director of national intelligence at the National Security Agency under George W Bush, tells Reuters this week that cyber war is more than a distant possibility. According to the current vice chairman at Booz Allen Hamilton, the US has already launched attacks on the computer networks of other nations.

McConnell did not add any input as to what countries have been hit with American cyber warfare in the past, but he did confirm that the US has already used the ability. When asked by Reuters if the United States had the capability to destroy the computer system of an adversary, McConnell responded “Yes.” When asked if it worked, he confirmed “yes” as well.

"Do we have the ability to attack, degrade or destroy? Sure. If you do that, what are the consequences? That is the question,” added McConnell.

Although the former spy chief neglected to name any countries that have been the target of American attacks, the US is believed by some to be the culprit behind a virus that targeted computer systems in Iran in 2010. Stuxnet, an advanced computer worm discovered in June of that year, impacted the computers used in conjunction with Iran’s nuclear program. In a January 2011 article in the New York Times, an American nuclear intelligence expert speaking on condition of anonymity said that the Israelis were behind Stuxnet, placing the blame on one of America’s most important allies. The expert adds in the article that Israel did indeed work hand-in-hand with the US in perfect Stuxnet before sending it to the Iranian networks, but that Washington wanted “plausible deniability.”

Other sources have since all but confirmed America’s involvement in the worm. German cyber security expert Ralph Langner told National Public Radio last year that the virus seemed like something out of science fiction, but added that, "Thinking about it for another minute, if it's not aliens, it's got to be the United States.” He went on to call the US “the leading force” behind Stuxnet, an assumption that many in Iran believe as well. While the Iranians have never officially recognized retaliation on their part, rumors of revenge via cyberwar have been rampant in recent weeks, particularly after news broke out of Mexico last month that hackers south of the border were being recruited by Iran to participate in an infiltration of American computers.

Before it launched an airstrike` attack on Libya in 2011, a cyberattack was considered as a route to oust Colonel Muammar Gaddafi, an Obama official said to the New York Times last year. In the end, however, America relied on other techniques. “These cybercapabilities are still like the Ferrari that you keep in the garage and only take out for the big race and not just for a run around town, unless nothing else can get you there,” the insider, speaking on condition of anonymity, told the Times.